Patent GB-1202850-A (GB)
Title: Transmission control
IPC: F16H61/26
Filed: 1969-06-05
Abstract: 1,202,850. Change-speed control. GENERAL MOTORS CORP. 5 June 1969 [15 July, 1968], No. 28542/69. Heading F2D. A shift-control lever 10 for the manual ranging valve 14 of an automatic transmission on a motor-vehicle has two modes of operation; firstly operating the valve directly by clockwise movement about its pivot 24 to select R (reverse), N (neutral) and P (park) from D (all three automatic ratios); and secondly in incremental ratchet-operated steps up or down for selecting 2 (second ratio) and 1 (first ratio), the lever 10 being spring-returned to D setting after each step. Ratchet-stepped down and up shifts are thus made by counterclockwise and clockwise movements respectively of the lever which always returns to D after the shift. Inadvertent up or down shift movements beyond D and 1 respectively have no effect. Selection of the two modes is effected by squeezing or releasing a detent-control member 46 in a transverse bar 29 of a V-shaped control handle 10, an additional and heavier squeeze being required to enter P setting. The control handle 10, pivoted at 24, actuates the ranging valve 14 through a similarlypivoted latching plate 81 to which is adjustably secured the end of a push-pull Bowden cable 93 operating the valve. For the first mode, selection between D, N R and P, the control handle 10 is connected directly to the latching plate 81 by squeezing the detent-control member 46 to an intermediate position, which, through connecting bars 36 running down the limbs of the control handle 10, raises a detent bar 41 into a slot 99 in the latching plate 81, giving direct operation. The latching plate 81 is located in D, R and P settings by notches D<SP>1</SP>, R<SP>1</SP>, P<SP>1</SP> in a fixed detent plate 51, P<SP>1</SP> being deeper to require and additional squeeze of the member 46 against a caged spring 45. Anticlockwise movement of the handle 10 beyond D setting is prevented by abutment of the detent bar 41 on a stop D<SP>1</SP> on the fixed detent plate 51, cleared only by releasing the detent control member 46. In the second mode, the ratchet-stepped shift between 1, 2 and D is effected through upshift and downshift pawls 101, 116 pivoted to the latching plate 81 at 102, 117 respectively, each pawl having two stepped cam surfaces 103, 104 and 119, 120 for contact with the detent bar 41 to determine the particular incremental shift it is to make. Presentation of the cam surfaces 103 &c. to the detent bar is controlled by stops 72, 123 on the fixed detent plate 51, which pivot the pawls radially in opposition to return springs 111, 126. Thus, prior to making a shift to 2 from D, contact of the tail of the downshift pawl 116 with the fixed pin 123 will have pivoted the pawl 116 to align its 3-2 cam surface 118 with the detent bar 41. The detent control member 46 in the handle 10 is first released to permit the detent bar 41 to leave the slot 99 in the latching plate and occupy a free area beneath it. On moving the handle 10 anticlockwise to 2 setting for 3-2 downshift, the detent-bar 41 now actuates the downshift pawl 116 through its 3-2 cam surface 118 to downshift the valveactuating detent-plate 81 through one increment, after which, on release, the control handle 10 is centralized back to D setting by the centralizing spring 72. The 3-2 step of the detent plate 81 causes the stop 123 to release the tail of the downshift pawl 116 which is then spring- moved outwards to present its 2-1 cam surface to the detent bar 41 ready for a subsequent 2-1 downshift, followed, as before, by centralizing of the control handle 10 to D setting. Upshifts in this mode, are similar, using the 1-2 and 2-3 cam surfaces 104, 103 on the upshift pawl 101.